Insulated conductor



July 18, 1939. c. R. COLBREE 2,166,796

INSULATED CONDUCTOR Filed Feb. 10, 1937 Inventor: Chester 1?. Colbree,

b H i S Att Orv? e g.

Patented July 18, 1939' UNITED STATES PATENT OFFICE INSULATED CONDUCTOR New York Application February 10, 1937, Serial No. 125,074

2 Claims.

This invention relates to insulated electrical conductors and more particularly to conductors of the concentric type in which a central conductor and its insulation are surrounded by a second conductor concentric therewith and the latter conductor provided with insulation. The invention has for its object to provide a readily flexible concentric conductor which shall be resistant to heat and of long life.

As indicated in the accompanying drawing, my improved conductor comprises a central core of stranded wire I about which is a thin layer of fibrous insulation 2, such as cotton, a layer of rubber 3 over the fibrous layer, a sheath or layer of felted asbestos 4 about the layer of rubber 3, over which the second conductor 5 consisting of a number of wires is laid up. Over the second conductor a layer of fibrous material 6 is applied and outside the latter is a sheath of rubber l which is prevented from adhering to the concentric wires by the fibrous layer.

The sheath of asbestos 4, over the rubber insulation 3 of the first conductor, serves to pro-' vide a smooth bed for the wires of the outer conductor 5 to move upon when flexed, to prevent the wires from working or cutting into the rubber under the efl'ect of flexure and to protect it against heat from the outer conductor. Moreover, asbestos on account of its being an inorganic material is not subject to decay, so that long life of my flexible conductor is insured irrespective of the use to which it may be put.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A concentric electric conductor comprising a central core having rubber insulation, a sheath of felted asbestos about said rubber insulation and in contact therewith, concentric wires laid up about said asbestos sheath and readily movable thereon upon flexure of the concentric conductor, and a protecting insulating sheath about said. concentric wires.

2. A flexible concentric electric conductor comprising a stranded central core surrounded by rubber insulation, a. sheath of felted asbestos about said rubber insulation and in contact therewith, a plurality of conductor wires laid up concentrically about said asbestos sheath and readily movable thereon upon flexure oi the concentric 'conductor, fibrous insulation disposed about said concentric wires, and;a rubber sheath about said fibrous insulation.

CHESTER R. COLBREE. 

